Microextraction by packed sorbent followed by ultra high performance liquid chromatography for the fast extraction and determination of six antidepressants in urine

The growing use of antidepressants in recent years has led to their increasing presence in forensic analyses. In this work, microextraction by packed sorbent followed by ultra‐performance liquid chromatography with photodiode array detection provided a fast method for determining the antidepressants mirtazapine, venlafaxine, escitalopram, fluoxetine, fluvoxamine, and sertraline in human urine. The microextraction conditions (viz., type of sorbent, number of draw–eject extraction cycles or strokes, sample volume and pH, and type and volume of washing solution and eluent) were optimized by using an experimental design. The ensuing analytical method was validated in terms of linearity (25–1000 ng/mL urine), limit of detection (lower than 7.1 ng/mL), limit of quantification (25 ng/mL), precision (4.7–15.1% as relative standard deviation), and accuracy (80.4–126.1% as mean recovery for four replicate determinations). The proposed method allowed the six target antidepressants to be determined at concentrations from therapeutic to toxic levels. The application to small volumes (300 μL) of urine afforded fast extraction of the analytes and provided results on a par with those of existing clinical and forensic alternatives.     

Separation and determination of ciprofloxacin in seawater,human blood plasma and tablet samples using molecularly imprinted polymer pipette‐tip solid phase extraction and its optimization by response surface methodology

By synthesizing a molecular imprinted polymer as an efficient adsorbent, ciprofloxacin was micro‐extracted from seawater, human blood plasma and tablet samples by pipette‐tip micro solid phase extraction and determined spectrophotometrically. Response surface methodology was applied with central composite design to build a model based on factors affecting on microextraction of ciprofloxacin; including volume of eluent solvent, number of extraction cycles, number of elution cycles, and pH of sample. Other factors that affect extraction efficiency, such as type of eluent solvent, volume of sample, type, and amount of salt were optimized with one‐variable‐at‐a‐time method. Under optimum extraction condition, pH of sample solution was 7.0, volume of eluent solvent (methanol) was 200 µL, volume of sample solution was 10 mL, and the number of extraction and elution cycles was five and seven, respectively, amount of Na₂SO₄ (as salt) and MIP (as sorbent) were optimized at 150 and 2 mg, respectively. The linear range of the suggested method under optimum extraction factors was 5–150 µg/L with a limit of detection of 1.50 µg/L for the analyte. Reproducibility of the method (as relative standard deviation) was better than 7%.     

Enantioselective determination of cathinones in urine by high pressure in‐line SPE–CE

This work presents a strategy based on the in‐line coupling of SPE and CE for the chiral determination of cathinones (R,S‐mephedrone, R,S‐4‐methylephedrine, and R,S‐ methylenedioxypyrovalerone) in urine samples, using a sample pretreatment based on liquid‐liquid extraction. The chiral separation of the compounds is achieved by adding a mixture of 8 mM 2‐hydroxypropil β‐CD and 5 mM β‐CD to the BGE, which consists of 70 mM of monosodium phosphate aqueous solution at pH 2.5. Oasis HLB was the selected sorbent for the in‐line SPE device, and to reduce analysis time and LODs, several parameters affecting the in‐line SPE system were evaluated, such as pressure and time of sample injection and dimensions of the SPE device. The highest preconcentration factors were achieved by using 3 bar of injection pressure for 20 min with an in‐line SPE device of 2 mm length and 150 µm of i.d. The developed method was applied to determine the presence of the compounds in spiked urine samples. The LODs obtained were between 3 and 8 ng/mL, and these levels were below the usual concentrations at which these drugs are present in urine from cathinone abusers. Thus, the optimized method has the potential to be applied for toxicological and forensic purposes.     

Development of a microextraction by packed sorbent with gas chromatography‐mass spectrometry method for quantification of nitroexplosives in aqueous and fluidic biological samples

A new method for quantification of 12 nitroaromatic compounds including 2,4,6‐trinitrotoluene, its metabolites and 2,4,6‐trinitrophenyl‐N‐methylnitramine with microextraction by packed sorbent followed by gas chromatography and mass spectrometric detection in environmental and biological samples is developed. The microextraction device employs 4 mg of C₁₈ silica sorbent inserted into a microvolume syringe for sample preparation. Several parameters capable of influencing the microextraction procedure, namely, number of extraction cycles, washing solvent, volume of washing solvent, elution solvent, volume of eluting solvent and pH of matrix, were optimized. The developed method produced satisfactory results with excellent values of coefficient of determination (R² > 0.9804) within the established calibration range. The extraction yields were satisfactory for all analytes (> 89.32%) for aqueous samples and (> 87.45%) for fluidic biological samples. The limits of detection values lie in the range 14–828 pg/mL.     

Determination of four bisphenols in water and urine samples by magnetic dispersive solid‐phase extraction using a modified zeolite/iron oxide composite prior to liquid chromatography diode array detection

A novel approach is presented to determine four bisphenols in water and urine samples, employing magnetic dispersive solid‐phase extraction combined with liquid chromatography and diode array detection. A modified zeolite‐based magnetic composite was used as an efficient sorbent, combining the advantages of magnetic materials with the remarkable properties of zeolites. A multivariate optimization design was employed to optimize some experimental factors affecting magnetic dispersive solid‐phase extraction. The method was evaluated under optimized conditions (i.e., amount of sorbent, 50 mg; sample pH, unadjusted; NaCl concentration, 1.25%; extraction and elution time, 2 min; eluent solvent, ethanol; eluent solvent volume, 400 µL), obtaining good linearity with correlation coefficients ranging between 0.995 and 0.999 (N = 5) (from 2 to 250 µg/L for bisphenol A, bisphenol AP, and bisphenol P and from 5 to 250 µg/L for bisphenol AF). Method repeatability was assessed obtaining coefficients of variation between 3 and 11% (n = 6). Finally, the method was applied to spiked real samples, obtaining for water samples relative recoveries between 83 and 105%, and for urine samples between 81 and 108% for bisphenol A, bisphenol AP, and bisphenol AF, and between 47 and 59% for bisphenol P.     

Quantitative determination of trace phenazopyridine in human urine samples by hyphenation of dispersive solid‐phase extraction and liquid‐phase microextraction followed by gas chromatography/mass spectrometry analysis

Magnetic dispersive solid‐phase extraction followed by dispersive liquid?liquid microextraction coupled with gas chromatography/mass spectrometry was applied for the quantitative analysis of phenazopyridine in urinary samples. Magnetic dispersive solid‐phase extraction was carried out using magnetic graphene oxide nanoparticles modified by poly(thiophene‐pyrrole) copolymer. The eluting solvent of this step was used as the disperser solvent for the dispersive liquid?liquid microextraction procedure. To reach the maximum efficiency of the method, effective parameters including sorbent amount, adsorption time, type and volume of disperser and extraction solvents, pH of the sample solution, and ionic strength as well as desorption time, and approach were optimized, separately. Characterization of the synthesized sorbent was studied by utilizing infrared spectroscopy, scanning electron microscopy, and energy‐dispersive X‐ray analysis. Calibration curve was linear in the range of 0.5?250 ng/mL (R² = 0.9988) with limits of detection and quantification of 0.1 and 0.5 ng/mL, respectively. Intra‐ and interday precisions (RSD%, n = 3) of the method were in the range of 4.6?5.4% and 4.0?5.5%, respectively, at three different concentration levels. Under the optimal condition, this method was successfully applied for the determination of phenazopyridine in human urine samples. The relative recoveries were obtained in the range of 85.0?89.0%.     

Magnetic micro‐solid‐phase extraction based on magnetite‐MCM‐41 with gas chromatography–mass spectrometry for the determination of antidepressant drugs in biological fluids

A new facile magnetic micro‐solid‐phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite‐MCM‐41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite‐MCM‐41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05–500 μg/L (r ² = 0.996–0.999). Good limits of detection (0.008–0.010 μg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n  = 5) for the determination of 0.1, 5.0, and 500.0 μg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1–115.4%. Results indicate that magnetite micro‐solid‐phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples.     

Preconcentration of organochlorine pesticides in aqueous samples by dispersive liquid–liquid microextraction based on solidification of floating organic drop after SPE with multiwalled carbon nanotubes

SPE joined with dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME‐SFO) as a novel technique combined with GC with electron‐capture detection has been developed as a preconcentration technique for the determination of organochlorine pesticides (OCPs) in water samples. Aqueous samples were loaded onto multiwalled carbon nanotubes as sorbent. After the elution of the desired compounds from the sorbent by using acetone, the DLLME‐SFO technique was performed on the obtained solution. Variables affecting the performance of both steps such as sample solution flow rate, breakthrough volume, type and volume of the elution, type and volume of extraction solvent and salt addition were studied and optimized. The new method provided an ultra enrichment factor (8280–28221) for nine OCPs. The calibration curves were linear in the range of 0.5–1000 ng/L, and the LODs ranged from 0.1–0.39 ng/L. The RSD, for 0.01 μg/L of OCPs, was in the range of 1.39–13.50% (n = 7). The recoveries of method in water samples were 70–113%.     

Dissolvable layered double hydroxide as a sorbent in dispersive micro‐solid phase extraction for the determination of acidic quinolones in honey by HPLC

This study presents a simple and green dispersive micro‐solid phase extraction method for preconcentration of acidic quinolones from honey prior to high performance liquid chromatography determination. A two‐dimensional nanostructured zinc‐aluminum layered double hydroxide was synthesized and used as the sorbent for dispersive micro‐solid phase extraction. Its different characteristics from conventional sorbents is that it is dissolvable in acidic solution (pH < 4). After the extraction, the analyte elution step was omitted and thus the use of organic solvents was avoided. The key parameters influencing the extraction efficiency such as the amount of sorbent, pH of sample solution, vortex time, type and volume of acidic solution were investigated and optimized. The method exhibited low limits of detection (3.0?5.0 ng/g), good linearity (10?2000 ng/g) with coefficients of determinations higher than 0.9991, acceptable precision (RSD<9.1%) and accuracy (RE<5.8%). The proposed method is fast, efficient, eco‐friendly, and suitable for the determination of acidic quinolones in honey samples.     

Hydrazide functionalized magnetic nanoparticles for specific extraction of N‐terminal serine and threonine peptides

In this study, we present hydrazide functionalized magnetic nanoparticles as a sorbent prepared by a new and facile method. Scanning electron microscope and Fourier transform infrared were used for characterizing the synthesized nanoparticles. The ability of the sorbent to extract N‐terminal serine and threonine peptides was evaluated. The peptides were modified by oxidation of the hydroxyl group in the 1,2‐amino alcohol structure before extraction. These aldehyde‐forms of peptides were specifically bonded to the hydrazide groups of the sorbent. The formed hydrazone bonds were cleaved in the presence of hydroxylamine reagent. Finally, the oximated peptides were released and quantified with a high‐performance liquid chromatography–diode array spectroscopy. The effects of experimental parameters including extraction time, elution time and elution volume on extraction efficiency were also investigated. The required time for the extraction process to reach equilibrium and elution time was only 8 h. The adsorption efficiency of the sorbent was 79 and 77% for peptides with N‐terminal serine and threonine, respectively. The sorbent showed good specificity for extracting the peptides. In addition, the extraction efficiency of the sorbent remained constant in the presence of a non‐N‐terminal serine and threonine peptide as interference.     

尿中莠去津去烃基代谢物的特丁二甲硅烷基衍生化/气相色谱-质谱联用分析法

建立了尿中除草剂莠去津(ATRZ)代谢物去乙基莠去津(DEA)、去异丙基莠去津(DIA)及去乙基去异丙基莠去津(DDA)的分析方法.尿样加入内标2-氨基-4-甲氧基-6-甲基-1,3,5-三氮嗪(AMMT),碱化后用高极性GDX501大孔树脂吸附、乙酸乙酯洗脱进行固相萃取,萃取物在乙腈溶剂中用N-甲基-N-特丁二甲硅烷...     

Polymer monolith microextraction online coupled to hydrophilic interaction chromatography/mass spectrometry for analysis of β2‐agonist in human urine

An analytical method based on online combination of polymer monolith microextraction (PMME) technique with hydrophilic interaction LC (HILIC)/MS is presented. The extraction was performed with a poly(methacrylic acid‐co‐ethylene glycol dimethacrylate) monolithic column while the subsequent separation was carried out on a Luna silica column by HILIC. After 1:1 v/v dilution with 20 mM phosphate solution at pH 7.0 and centrifugation, urine sample was directly used for extraction. After optimization, 85% ACN (containing 0.3% formic acid v/v) was used for rapid online elution, which was also the mobile phase in HILIC to avoid band broadening during separation or carry‐over that was usually observed in PMME‐RP LC system. Online automation of extraction and separation procedures was realized under the control of a program in this study. The developed method was applied to rapid and sensitive monitoring of three β₂‐agonist traces in human urine. The LODs (S/N = 3) of the method were found to be 0.05–0.09 ng/mL of β₂‐agonists in urine. The recoveries of three β₂‐agonists spiked in five different urine samples ranged from 79.8 to 119.8%, with RSDs less than 18.0%.     

Simple and rapid determination of phthalates using microextraction by packed sorbent and gas chromatography with mass spectrometry quantification in cold drink and cosmetic samples

A simple and rapid method using microextraction by packed sorbent coupled with gas chromatography and mass spectrometry has been developed for the analysis of five phthalates, namely, diethyl phthalate, benzyl‐n‐butyl phthalate, dicyclohexyl phthalate, di‐n‐butyl phthalate, and di‐n‐propyl phthalate, in cold drink and cosmetic samples. The various parameters that influence the microextraction by packed sorbent performance such as extraction cycle (extract–discard), type and amount of solvent, washing solvent, and pH have been studied. The optimal conditions of microextraction using C₁₈ as the packed sorbent were 15 extraction cycles with water as washing solvent and 3 × 10 μL of ethyl acetate as the eluting solvent. Chromatographic separation was also optimized for injection temperature, flow rate, ion source, interface temperature, column temperature gradient and mass spectrometry was evaluated using the scan and selected ion monitoring data acquisition mode. Satisfactory results were obtained in terms of linearity with R² >0.9992 within the established concentration range. The limit of detection was 0.003–0.015 ng/mL, and the limit of quantification was 0.009–0.049 ng/mL. The recoveries were in the range of 92.35–98.90% for cold drink, 88.23–169.20% for perfume, and 88.90–184.40% for cream. Analysis by microextraction by packed sorbent promises to be a rapid method for the determination of these phthalates in cold drink and cosmetic samples, reducing the amount of sample, solvent, time and cost.     

Self‐made microextraction by packed sorbent device for the cleanup of polychlorinated biphenyls from bovine serum

Microextraction by packed sorbent, a miniaturized form of the solid‐phase extraction, is a new sample pretreatment technology mainly used for bioanalysis. In this work, self‐made device was fabricated by packing C₁₈ sorbent into a microinjection needle (50 μL) and then applied for the analysis of polychlorinated biphenyls in bovine serum followed by gas chromatography with mass spectrometry determination. Compared with conventional solid‐phase extraction, the developed method bears many intriguing properties such as low consumption of the sample and organic solvent, time‐saving and easy operation, which are of great interest and desire for bioanalysis applications. A series of parameters that affect the analytical performance, such as the type of elution, the aspirating/dispensing cycles of sample loading and elution, washing solution, and matrix effects, was investigated in detail. Under the optimized conditions, the proposed method presented a good linearity (R ≥ 0.986) and satisfactory sensitivity and limits of detection (0.06–0.53 ng/mL) and quantification (0.20–1.77 ng/mL), respectively. In addition, satisfactory recoveries (60.0–91.4%) and accuracy (RSD ≤ 5.72%) were achieved after optimizing the conditions when applying the developed method to real sample analysis. The screening of polychlorinated biphenyls residues in bovine serum samples by the developed method demonstrated that the assay is ideally suited as a monitoring method for polychlorinated biphenyls residues in bioanalysis.     

Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid‐phase dispersion with vortex‐assisted dispersive liquid–liquid microextraction and HPLC with diode array detection

A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid‐phase dispersion combined with vortex‐assisted dispersive liquid–liquid microextraction and high‐performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid‐phase dispersion and the eluate obtained was concentrated and further clarified by vortex‐assisted dispersive liquid–liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6–2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples.     

Magnetic molecularly imprinted composite for the selective solid‐phase extraction of p‐aminosalicylic acid followed by high‐performance liquid chromatography with ultraviolet detection

A new method for the selective extraction of p‐aminosalicylic acid from aqueous and urine samples has been developed using magnetic molecularly imprinted polymer nanoparticles before determination by high‐performance liquid chromatography. The Fe₃O₄ nanoparticles were first prepared through the chemical coprecipitation of Fe²⁺ and Fe³⁺ and then coated with a vinyl shell. Subsequently, a layer of molecularly imprinted polymers was grafted onto the vinyl‐modified magnetic nanoparticles by precipitation polymerization. FTIR spectroscopy, scanning electron microscopy, vibrating sample magnetometry, and thermogravimetric analysis were applied to characterize the sorbent properties. Moreover, the predominant parameters affecting the magnetic solid phase extraction such as sample pH, sorption and elution times, the amount of sorbent, and composition and volume of eluent were investigated thoroughly. The maximum sorption capacity of the imprinted polymer toward p‐aminosalicylic acid was 70.9 mg/g, which is 4.5 times higher than that of the magnetic nonimprinted polymer. The magnetic molecularly imprinted polymer nanoparticles were applied for the selective extraction of p‐aminosalicylic acid from aqueous and urine samples and satisfactory results were achieved. The results illustrate that magnetic molecularly imprinted polymer nanoparticles have a great potential in the extraction of p‐aminosalicylic acid from environmental and biological matrices.     

Determination of catecholamines in urine using aminophenylboronic acid functionalized magnetic nanoparticles extraction followed by high‐performance liquid chromatography and electrochemical detection

A new method was developed for the simultaneous determination of three catecholamines in urine using aminophenylboronic acid functionalized magnetic nanoparticles extraction followed by high‐performance liquid chromatography with electrochemical detection. Novel aminophenylboronic acid functionalized magnetic nanoparticles were prepared by multi‐step covalent modification, and characterized by transmission electron microscopy, Fourier‐transformed infrared spectroscopy, X‐ray diffraction, and vibrating sample magnetometry. With the help of the high affinity between the boronate and cis‐diol group, the particles were used for the highly selective separation and enrichment of three major catecholamines, norepinephrine, epinephrine, and dopamine. Effects of the pH of the feed solution, the extraction time, the composition of the buffer solution, the amount of the magnetic particles, the elution conditions, and the recycling of aminophenylboronic acid functionalized magnetic nanoparticles were explored. Under the optimized conditions, 13–17‐fold enrichment factors were obtained. The linear ranges were 0.01–2.0 μg/mL for the studied analytes. The limits of detection and quantification were in the range of 2.0–7.9 and 6.7–26.3 ng/mL, respectively. The relative recoveries were in the range of 92–108%, with intraday and interday relative standard deviations lower than 6.8%. This method was successfully applied to analysis of catecholamines in real urine.     

Hydrophilic solid‐phase extraction of melamine with ampholine‐modified hybrid organic–inorganic silica material

In this work, an ampholine‐functionalized hybrid organic–inorganic silica sorbent was successfully used to extract melamine from a milk formula sample by a hydrophilic interaction solid‐phase extraction protocol. Primary factors affecting the extraction efficiency of the material such as extraction solvent, elution solvent, sample loading volume, and elution volume have been thoroughly optimized. Under the optimized hydrophilic solid‐phase extraction conditions, the recoveries of melamine spiked in milk formula samples ranged from 86.2 to 101.8% with relative standard deviations of 4.1–9.4% (n = 3). The limit of detection (S/N = 3) was 0.32 μg/g. The adsorption capacity toward melamine was 30 μg of melamine per grams of sorbent. Due to its simplicity, rapidity and cost effectiveness, the newly developed hydrophilic solid‐phase extraction method should provide a promising tool for daily monitoring of doped melamine in milk formula.     

Nitrogen doped nano porous graphene as a sorbent for separation and preconcentration trace amounts of Pb,Cd and Cr by Ultrasonic assisted in‐syringe dispersive micro solid phase extraction

Nitrogen doped nano porous graphene was used as an efficient sorbent in solid‐phase extraction process for simultaneous separation and pre‐concentration of metal ions lead (II), cadmium(II), and chromium(III)) in biological samples. Ultrasonic assisted in‐syringe dispersive micro solid phase extraction coupled with micro sampling atomic absorption spectrometry was utilized for the determination of metal ions. Nitrogen doped nano porous graphene was synthesized as a nano sorbent by chemical vapour deposition method. Methane and aniline were used as carbon and nitrogen sources. The characterization of sorbent was performed by field emission scanning electron microscope, transmission electron microscopy, atomic force microscope, fourier transform infrared, chemical element analysis and raman analysis. Effective parameters on the extraction efficiency such as pH, sorbent dosage, eluent volume and eluent concentration were optimized by central composite design and desirability function. Experimental results indicate that the optimal conditions for this extraction were pH = 6.4, 1.42 mg of sorbent, 100 μL of eluent, and 0.84 mol L^‐1 of eluent concentration. The detection limits are as low as 1.5, 0.3 and 0.9 μg L^‐1 for lead, cadmium, and chromium, respectively. The intra‐day precisions were 3.6, 4.38 and 2.94 and Inter‐day precision were 4.83, 5.26 and 4.52 for lead, cadmium, and chromium, respectively. Method performance was investigated by determination of mentioned heavy metals in complicated biological matrixes such as human plasma, urine and saliva samples with good recoveries.     

Application of microextraction by packed sorbent to isolation of psychotropic drugs from human serum

A method of microextraction by packed sorbent (MEPS) followed by liquid chromatography with diode array detection has been developed and optimized for the extraction of six tricyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine, doxepin, nordoxepin) from human serum. The optimal parameters of MEPS extraction (type of sorbent, volume of sample, composition, and volume of washing and elution solutions) for these drugs in spiked samples were defined. The developed MEPS procedure was validated and then successfully applied to the analysis of serum reference material. The limit of detection (0.02–0.05 μg/mL), intraday (2.7–8.8%) and interday (4.4–11.6%) precision (RSD), and the accuracy of the assay (94.5–108.8%) at three concentration levels—0.2, 0.5, and 0.8 μg/mL—were estimated. The accuracy of the method was evaluated by the analysis of certified reference material. Moreover, the validated procedure was compared with the solid-phase extraction technique. Finally, microextraction by packed sorbent was assessed as a suitable tool in forensic and clinical methods for serum sample preparations.